Previously to the biological monitoring campaigns the RIVEAL project teams gathered in the River Alva to test the sampling methodology. The biological elements sampled in this project are macroinvertebrates, diatoms, algae, bryophytes, macrophytes and riparian vegetation. Field sampling is performed in every mesohabitat of each sampling site. Physicochemical and ecohydraulic parameters are also recorded in every of the surveyed mesohabitats.